The present invention relates to etching an etch layer through a mask during the production of a semiconductor device. More specifically, the present invention relates to etching a dielectric layer through a pseudo-hardmask, such as amorphous carbon or polysilicon during the production of semiconductor devices. Amorphous carbon is a deposited high temperature carbon layer using a deposition process, such as chemical vapor deposition (CVD) with some hydrogen. Such amorphous carbon layers may be deposited at temperatures greater than 400° C.
During semiconductor wafer processing, features of the semiconductor device are defined in the wafer using well-known patterning and etching processes. In these processes, a photoresist (PR) material may be deposited on the wafer and then is exposed to light filtered by a reticle. The reticle may be a transparent plate that is patterned with exemplary feature geometries that block light from propagating through the reticle.
After passing through the reticle, the light contacts the surface of the photoresist material. The light changes the chemical composition of the photoresist material such that a developer can remove a portion of the photoresist material. In the case of positive photoresist materials, the exposed regions are removed, and in the case of negative photoresist materials, the unexposed regions are removed, resulting in a patterned photoresist mask. The pattern may be transferred from the patterned photoresist mask to a pseudo-hardmask layer, which may use an intermediate hardmask layer. Thereafter, the wafer is etched to remove the underlying material from the areas that are no longer protected by the pseudo-hardmask, and thereby produce the desired features in the wafer. The use of a pseudo-hardmask allows deeper etching at high resolution.